Wasn't there a really big article about this?
http://www.theverge.com/2017/6/13/15782200/one-device-secret...
The gist of it is the entire company wanted to do a phone because of how cool it would be. The work of three secret teams unbeknownst to Steve Jobs came together in just the right ways to make the iPhone.
No one did, though. Go back and watch that keynote — there's thunderous applause for the iPod and phone portions of that sentence, and (relative) awkward silence for the "internet communicator" bit.
Reading through the Jobs biography, there's a great segment on the development of the iPod wherein Tony Fadell (I believe) details how he was coached to present the best mockups to Steve last.
Given the ordering of the three statements in that sentence you quoted, I have to imagine that someone at Apple — maybe not Steve — understood the eventual ubiquity of the smartphone.